Manual: Beam weapons¶
Beam accuracy depends mainly on the firing ship's Beam Attack, the target's Beam Defense, and distance. Better computers and scanners help you hit; faster targets and longer ranges make hits less likely. Mounts and weapon modifications can change both accuracy and damage, so the same weapon can behave quite differently between designs.
Accuracy¶
Several things determine the chance to hit, but it boils down to three factors: Beam Attack, Beam Defense and Range Penalty.
Beam Attack modifiers¶
Beam Attack (BA) is a way of rating the firing ship’s beam offense capability. It is calculated based on the type of computer on board, ship systems like battle scanner, crew experience, leaders and racial bonuses. Battlestation and Star Fortress give an additional BA bonus of +10 and +20 respectively to all ships in the defensive fleet. Individual beam weapons get additional bonuses based on mount type (PD +25 BA) and mods (Co +25 BA, AF -20 BA).
Beam Defense modifiers¶
Beam Defense (BD) is a rating of the target ship's dodging ability, calculated from 5 times its combat speed plus bonuses from ship systems such as an Inertial Stabilizer, crew experience, leaders, and race. A ship with zero current speed uses -20 as its speed contribution instead of 0, making an immobilized ship easier to hit.
Beam Defense of missiles¶
Missile Beam Defense is calculated as follows:
Missile Beam Defense = 5 * Speed + MissileBonus
Speed = Missile BaseSpeed + 2 * (FTLlevel - 1)
BaseSpeed is 12 for Nuclear, Merculite, Pulson, and Zeon missiles. The Fast modification adds 4 to tactical movement speed, but it is not included in this defensive speed calculation.
| Drive | FTLlevel |
Speed | Missile | MissileBonus |
|---|---|---|---|---|
| None | 0 | 10 | Nuclear | -10 |
| Nuclear | 1 | 12 | Merculite | 15 |
| Fusion | 2 | 14 | Pulson | 40 |
| Ion | 3 | 16 | Zeon | 70 |
| Anti-Matter | 4 | 18 | - | - |
| Hyper | 5 | 20 | - | - |
| Interphased | 6 | 22 | - | - |
Beam Defense of fighters¶
Fighter Beam Defense is calculated as follows:
Fighter Beam Defense = 5 * Speed + RacialShipDefenseBonus + FighterPilotBonus + HelmsmanBonus
Speed = Fighter BaseSpeed + 2 * (FTLlevel - 1) + TDBonus
TDBonus is 4 when the fighter belongs to a Trans-Dimensional race and 0 otherwise. The Fast modification adds 4 to a fighter's tactical movement speed, but it is not included in this defensive speed calculation. Fighter Pilot and Helmsman use the best applicable active fleet-leader bonuses.
| Fighter | BaseSpeed |
|---|---|
| Interceptor | 10 |
| Assault Shuttle | 6 |
| Bomber | 8 |
| Heavy Fighter | 8 |
Range penalty to accuracy¶
The farther away a target is, the less likely it becomes for a beam weapon to hit it. The range penalty to a beam’s accuracy comes from below table:
| Range | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|---|
| Penalty | 0 | 0 | 10 | 20 | 30 | 40 | 55 | 70 | 85 |
One range unit equals 3 squares. At range 0 two opponents share the same square, for example when interceptors are on top of the target ship. At range 1 opponents are adjacent to each other or have 1-2 squares between them.
For calculation purposes, Point Defense weapons get a penalty as if range is doubled and for Heavy mount weapons the actual range is halved (and rounded down):
| Range | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|---|
| Regular (sq) | 0 | 1-3 | 4-6 | 7-9 | 10-12 | 13-15 | 16-18 | 19-21 | 22-24 |
| PD (sq) | 0 | - | 1-3 | - | 4-6 | - | 7-9 | - | 10-12 |
| Hv (sq) | 0-3 | 4-9 | 10-15 | 16-21 | 22-27 | 28-33 | 34-39 | 40-45 | 46-51 |
| Penalty | 0 | 0 | 10 | 20 | 30 | 40 | 55 | 70 | 85 |
Classic Fusion Beam, Plasma Cannon, Mauler Device, and Plasma Breath originally had an inherent 2x range-to-hit penalty. This property doubles the calculated penalty after mount effects and the Rangemaster Unit are applied.
Version 1.50 removes the property from Mauler Device and Plasma Breath. Mauler Device always hits except against a Displacement Device, so the removed range penalty would not otherwise affect it. The bundled 1.50 Improved mod also removes the property from Fusion Beam, leaving only Plasma Cannon with it.
Classic chance-to-hit formula¶
The game rolls a random number from 1 through 100 and applies these checks in order:
- A lucky shot hits for maximum damage:
random(100) > 95
- Otherwise, overwhelming attack strength hits for maximum damage:
BA + CO - AF - BD >= 99
- Otherwise, the normal accuracy check determines whether the beam hits:
random(100) + BA + CO - AF - BD >= hit_threshold
hit_threshold = min(40 + range_penalty - PD_bonus, 95)
The range_penalty is doubled for a weapon with the inherent 2x range-to-hit penalty.
In simplified mode, the third check uses the fixed threshold of 40 rather than the range-adjusted hit_threshold used by the classic damage calculation below.
Thus, if the random number is greater than 95 (a 5% lucky shot, no matter the odds), or BA + CO - AF - BD is larger than 98, the beam strikes the target. Otherwise, BA + CO - AF - BD minus the range penalty, plus any PD bonus, must be 39 or higher to ensure a hit.
- Mauler Device and Energy Absorber always hit unless the target ship has a Displacement Device.
- Stellar Converter always hits regardless of the presence of a Displacement Device.
The value 40 in hit_threshold can be changed with combat hit_threshold_fixed_value = 40;.
Optional 1.50 alternative chance-to-hit formula¶
The chance-to-hit formula contains a major flaw: range penalties, though important in theory, can have little or no effect. Formula [3] caps the threshold at 95, so range penalties above 55 for a non-PD beam or 80 for a PD beam have no additional effect. Formula [2] can also ignore range entirely when BA is high and BD is low. This creates sure-hit-at-any-distance situations, reduces the usefulness of the Rangemaster Unit compared with the Battle Scanner, and weakens the inherent 2x range-to-hit penalty.
Setting combat simplified_beam_formula = true; enables a more straightforward way of calculating chance to hit, with distance penalties consistently affecting chance:
- A lucky shot hits for maximum damage:
random(100) > 95
- Otherwise, overwhelming attack strength hits for maximum damage:
BA + CO - AF - BD - range_penalty + PD_bonus >= 99
- Otherwise, the normal accuracy check determines whether the beam hits:
BA + CO - AF - BD - range_penalty + PD_bonus + random(100) >= 40
In both checks, range_penalty is doubled for a weapon with the inherent 2x range-to-hit penalty.
Damage Potential¶
If a beam hits, it needs to be determined how much damage it does.
There are 2 pairs of beam weapon types, affecting damage distribution:
- Not reduced by range / Reduced by range.
- Equal min-max damage / Different min-max damage.
Damage values of both types are later modified with Hv, PD, HEF and Ordnance effects.
Not reduced by range¶
For weapons whose damage is not reduced by range, such as Mass Driver, Gauss Cannon, and Disruptor, no dissipation penalty applies. In cases of low accuracy, a Laser Cannon with the NR modification can still deal less than 4 damage.
Example: The lowest damage at range for an NR beam with base damage 10-40 is 10, whereas a regular 10-40 beam can deal as little as 4.
Reduced by range¶
For weapons of which the damage is reduced by range (dissipation), a penalty based on the distance the beam must travel to the target is taken into account. This penalty lowers the damage potential. (Round to nearest applies and the minimum damage potential is always 1.) Below table of damage potential by range includes examples for Laser Cannon, Phasor, Mauler and Death Ray:
| Range (sq) | 0 | 1-3 | 4-6 | 7-9 | 10-12 | 13-15 | 16-18 | 19-21 | 22-24 |
|---|---|---|---|---|---|---|---|---|---|
| Penalty | 0 | 0 | -10 | -20 | -30 | -40 | -50 | -60 | -65 |
| Damage | 100% | 100% | 90% | 80% | 70% | 60% | 50% | 40% | 35% |
| Laser | 1-4 | 1-4 | 1-4 | 1-3 | 1-3 | 1-2 | 1-2 | 1-1 | 1-1 |
| Phasor | 5-20 | 5-20 | 5-18 | 4-16 | 4-14 | 3-12 | 3-10 | 2-8 | 2-7 |
| Mauler | 100 | 100 | 90 | 80 | 70 | 60 | 50 | 40 | 35 |
| Death Ray | 50-100 | 50-100 | 45-90 | 40-80 | 35-70 | 30-60 | 25-50 | 20-40 | 18-35 |
Equal minimum and maximum damage¶
For Mauler Device, minimum and maximum damage are equal, so actual damage is known after applying dissipation and the Hv, PD, HEF, and Ordnance effects. If the beam hits, the resulting minimum damage is applied. Weapons with different minimum and maximum damage require an additional calculation.
Different minimum and maximum damage¶
With the classic beam formula, actual damage for weapons with different minimum and maximum damage is based on the damage potential modified by the accuracy of the shot:
The uncapped damage is:
uncapped_damage = min_dmg + (max_dmg - min_dmg + 1) * A / B
The formula uses these intermediate values:
A = roll_plus_attack - hit_threshold
B = 100 - hit_threshold
roll_plus_attack = min(random(100) + BA + CO - AF - BD, 100)
hit_threshold = min(40 + range_penalty - PD_bonus, 95)* doubled for inherent 2x range to-hit penalty mod
The overall result is capped at max_dmg.
Examples¶
- Death Ray damage at 23 squares, assuming
roll = 85andBA + CO - AF - BD - range_penalty = 10:
18 + (35 - 18 + 1) * A / B
A = (85 + 10) - (40 - -85) = 95 - 95 = 0
B = 100 - (40 - -85) = 100 - 95 = 5
Thus, actual damage equals min_dmg, or 18.
- If the target is closer, at 11 squares:
35 + (70 - 35 + 1) * A / B
A = (85 + 10) - (40 - -30) = 95 - 70 = 25
B = 100 - (40 - -30) = 100 - 70 = 30
The actual damage is therefore min_dmg + ⅚ * (max_dmg - min_dmg + 1), or 65.
Hv, PD, HEF, and Ordnance¶
These bonuses are percentages of damage of a regular mount beam. (In 1.50 the HEF bonus can be set for each mount separately.) Their interaction is not multiplicative but additive and they work the same way as dissipation range penalty, modifying min&max damage, so these bonuses are not subject to dissipation themselves.
Ordnance works best for regular ship beams because their modified damage is rounded to the nearest whole point, while fighter payloads are truncated. A 10% Ordnance bonus therefore raises a 5-damage ship beam to 6 after rounding, while a 5-9 damage fighter beam or missile still gains no whole point at its lower end.
Examples for a 50-100 beam with a dissipation range_penalty of 30 follow.
Heavy mount¶
50 * (100 {base} + 50 {Hv} - 30 {range_penalty})% = 60
100 * (100 {base} + 50 {Hv} - 30 {range_penalty})% = 120
Heavy mount with High Energy Focus¶
50 * (100 {base} + 50 {Hv} + 50 {HEF} - 30 {range_penalty})% = 85
100 * (100 {base} + 50 {Hv} + 50 {HEF} - 30 {range_penalty})% = 170
Point Defense mount¶
50 * (100 {base} - 50 {PD} - 30 {range_penalty})% = 10
100 * (100 {base} - 50 {PD} - 30 {range_penalty})% = 20
For a Point Defense beam whose 2x range penalty also applies to dissipation:
50 * (100 {base} - 50 {PD} - 2 * 30 {range_penalty})% = -5
100 * (100 {base} - 50 {PD} - 2 * 30 {range_penalty})% = -10
In this case, both actual damage values become the minimum of 1. At maximum distance, every Point Defense beam reduced by range likewise does only 1 damage without High Energy Focus or Ordnance, regardless of its listed maximum damage.
With High Energy Focus added:
50 * (100 {base} - 50 {PD} + 50 {HEF} - 2 * 30 {range_penalty})% = 20
100 * (100 {base} - 50 {PD} + 50 {HEF} - 2 * 30 {range_penalty})% = 40